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Abstract

Successful contraception in wildlife requires both an efficacious and safe contraceptive agent and an efficacious and safe method of delivering that agent to the animal. Remote delivery systems (RDS)-mechanical devices capable of administering a single dose to an unrestrained animal, usually by means of a ballistic projectile-can target specific animals and facilitate the administration of contraceptives on a body weight basis. Liquid, solid, and semisolid formulations can be delivered via RDS, and sometimes treatment costs can go down with this methodology. Disadvantages of RDS include the fact that many of them can be used only on larger animals and RDS’ inherent complexity increases the probability of administration failure. Most RDS use a powered gun to deliver either a dart or biobullet containing the contraceptive product. Biobullet RDS are capable of treating many animals rapidly. Both darts and biobullets can be designed to deliver different formulations to provide controlled release of contraceptives at a predetermined rate for a given period. The four general classes of controlled release systems (mechanical pumps, osmotic pumps, chemically controlled systems, and diffusional systems) are discussed. Chemically controlled and diffusional systems comprised of biodegradable polymers offer the most promise for single-dose, prolonged contraceptive release that can be remotely delivered to wildlife.